BOUNTIFUL — Motorists using I-15 through Davis County will find travel overnight slower, as the Utah Department of Transportation begins work on the county's first diverging diamond interchange (DDI) on Friday, May 9..

The work is part of the I-15 South Davis Improvement Project that recently got underway. Crews will begin to remove sections of the I-15 bridge over 500 South in preparation to replace the bridge.

"During demolition, 500 South in Bountiful will be closed from 10 p.m. to 9 a.m. Saturday morning, and I-15 will be reduced to one lane in both directions,” said Vic Saunders, Region One communications manager. “Local traffic can use 400 North as an alternate route and I-15 traffic can use 2600 South, or 500 West (Exit 317, SB US-89).”

The DDI is an interchange concept in which both directions of traffic are crossed to the opposite side to provide easier access on and off the freeway, said Nathan Peterson, UDOT Region One project manager. “DDI’s efficiently move high volumes of traffic through an interchange without increasing the number of lanes.

The interchange reduces the number of traffic signals needed to move motorists through the interchange to two, instead of the usual three or four usually needed.

Since 2010, UDOT has constructed DDIs at four locations: I-15 in American Fork at Main St. and 500 East; I-15 in Lehi at Timpanogos Highway; and Bangerter Highway in Salt Lake at 2100 South. UDOT is also constructing DDIs at 1100 South in Brigham City and at exit 57 in Cedar City. For more information on the construction project, or to sign up for email updates, visit www.udot.utah.gov/i15southdavis.